[vbs_muc]

Hi there,

I was wondering if anyone has some hints about how to setup a scene so that I can render the way the sample image shows it (it's a photo I guess).
I'm looking for a setup with a pure white underground, yet soft model shadows on the floor.

http://farm4.static.flickr.com/3102/267 ... 1d.jpg?v=0

My first attempts were not satisfying, because the model itself was always too bright, or, when I reduced light, the floor became grey.
I used 100% diffuse plastics (no reflections) for the floor material, but I just can't get it to be white. Do I need a special emitter for this or a special material? How can I render on a really white ground?

Thanks for any comments...

Roberto

[Becco_UK]

Have you tried testing an emitter layer on your floor material? With Multilight active you might be able to adjust lighting so that the floor still looks ok but white.

[Bubbaloo]

Have you tried testing an emitter layer on your floor material? With Multilight active you might be able to adjust lighting so that the floor still looks ok but white.

You might lose your shadows doing that.
How about using sky dome with a 98% roughness 230,230,230 diffuse material for the surface? Then add emitters for highlights/shadows.

[Becco_UK]

Bubbaloo: Yes, but if necessary you can composite a seperate shadow render in.

[Bubbaloo]

Good idea.

[vbs_muc]

Thanks guys,

I will try to work with multilight/emitter setups with skydome enabled, haven't done that before to be honest. I always disabled skydome...
Is there a difference between a 100% rough, white material and the above suggested 98% roughness 230,230,230 diffuse material?...

The emitter as floor material trick was also suggested by a friend of mine who is a professional photographer. She said they sometimes use satin glas for the ground to get shadow and reflections, and then lighten it from underneath for a bright white appearance. Maybe I'll give it a try as well.

I will report results soon...

By the way, talking about emitters, is there a description of the emitter-types somewhere? (halogem, compact, fluorescent etc...?)... How do they act, what to use for which purpose? ....

Thanks again for your posts,

Greets from Munich
Roberto

[Mihai]

The presets are there more for architectural visualisation, they have a typical color and strength based on common light sources. Other than that there is no difference between the presets and setting up your own emitters.

I wouldn't use skydome if you want your object to have some nice contrast as well. In the example you posted you can see the environment is mostly black, with an emitter somewhere to the left and not so big relative to the object judging by the shadows. To get the floor almost white it's more a matter of controlling the exposure and emitter strength. Try setting the floor whiter, at 240 and if it's just flat like this you can leave it as Lambert (100% roughness). You don't need a plastic material for it, a one bsdf material is enough. You should uncheck lambert for most materials if they are applied to anything but simple flat objects since you loose some definition on the object when using Lambert.

Left lambert, right roughness 99:

[majipoor]

I've done quite a lot of photography of such "objects on white" and as Maxwell is supposed to mimic real light behaviour, I would say that you should not spend too much time trying to achieve the result you want directly in Maxwell.

With a real photo, I think it is impossible(?) to get a white floor in this case without overexposing the object and/or killing the shadows because it stands directly on the floor (otherwise you would have to use a flash to light the floor to allow a difference of 2-3 f/stops in exposure between the floor and the object which is necessary to achieve a nice isolation on white).

As with a photo, I would say the easiest way to achieve the result you want is to accept a slightly gray floor when rendering and then post-process your picture in Photoshop.

My first post in this forum

Hello everybody!

[Bubbaloo]

Welcome to the forums, and good advice.

Although Maxwell is advertised as physically correct, there are things you can do that are not possible in the real world such as 100% lambertian materials. So it's not just a matter of trying to create a setup that mimics a real life photography setup. There are "tricks" to be used, and that is what the originator of this topic is after, I think.

[hyltom]

No post


With little post (simply to match the reference photo)


To light this scene, i used an LDR picture that you can find here with intensity set to 2.

For the floor material i use one bsdf layer with roughness 99%, reflectance 0 (245,245,245).

My camera f-stop is 22, with shutter speed at 2.4 and ISO 100...lens 50mm.

[Becco_UK]

hyltom: That works nice. Thanks for the image downloads too.

[majipoor]

Nice one! But this is something you could also achieve with a real photo without post-processing: the floor is not pure white

But I have a question now: is there any advantage to use such HDR maps instead of simple plane emitters to simulate a softbox? Just wondering.

[Mattia Sullini]

Thanks a lot, hyltom. I missed your thread when you posted it.

The reference photo looks quite postprocessed to me... and i believe there should be a white reflection card somewhere above the object, shifted towards the background

[hyltom]

the floor is not pure white

Yes, like the reference photo...also i specially choose a light color (offwhite) to show that it's possible to render white on white. Now if i had to render just the stainless steel product on the pure white background, it will not be difficult to achieve by decreasing the shutter speed.